The entertainment industry is in the midst of a digital revolution. Music, television, and movies are increasingly becoming digital, offering new advantages to the consumer in quality and flexibility. At the same time the digital revolution also comprises a threat since digital data can be perfectly and quickly copied. If consumers may freely copy entertainment content and offer that content on the Internet, the market for entertainment content would evaporate.
The rapid growth in the distribution of recordable media over the Internet, such as MP3s and DVDs, is especially alarming to content owners. These highly controversial and unauthorized distribution channels have caused an increase in demand from the entertainment industry for methods to protect their multi-million dollar content. Developing a content protection system that offers content owners an end-to-end solution they can use to securely distribute their media is becoming increasingly important as the amount of content shared across the Internet grows exponentially each year.
Recently, developments in consumer electronics have created an alternative to traditional digital rights management systems. New recording and playing devices that use this new method, known as CPRM (Content Protection for Recordable Media) technology, have reached the market. It is now possible to directly record content protected in CPRM to writable media. If the recording is prepared in a server the client needs no special keys or tamper-resistance. This method of content protection utilizes broadcast encryption. Devices do not need to have a conversation to establish a common key. Recent advances in broadcast encryption have made it as powerful as public-key cryptography in terms of revocation power. Because of its one-way nature, broadcast encryption is inherently suited to protect content on storage.
Once the client receives the encrypted recordable media content using CPRM, the interaction between the content server and the client side module is complete. The server is now free to focus on other requests. On the client side, CPRM requires that the encrypted content be recorded onto a physical piece of media, such as a DVD. This recording is performed in such a way that the encrypted content can only be played by a compliant device while it is on that particular piece of media. Consequently, encrypted content copied to another physical piece of media cannot by played by a compliant device.
CPRM devices use the media key block and media ID located currently on blank DVD recordable disks to calculate a media unique key. The media unique key is used to encrypt title keys. In turn, the title keys encrypt the content stored on the DVDs. Encrypting the title keys in the media unique key causes the title keys to become cryptographically bound to the particular piece of physical media on which the content is burnt. This prevents the content from being decrypted and accessed from any other physical piece of media.
Although this technology has proven to be useful, it is desirable to present additional improvements. In a server-based CPRM system, the calculation that binds the title key to the media is performed on the server-side, not the client-side. However, there is currently no means by which the server may learn the title key other than storing the title key in a database. Such a database is difficult to maintain in a secure and tamper-resistant environment.
What is therefore needed is a system, a computer program product, and an associated method for protecting a title key while providing means for the clearinghouse server to learn the title key. The need for such a solution has heretofore remained unsatisfied.